Coating mineral moldings

Abstract

The present invention relates to a process for coating mineral moldings with film-forming aqueous formulations in which in succession at least one 1st formulation comprising at least one copolymer P1 as binder and at least one inorganic pigment is applied to the mineral molding and, if desired, is dried and then at least one 2nd formulation comprising at least one copolymer P2 as binder and, if desired, inorganic pigment is applied, the copolymers P1 and P2 each being composed of monomers A, B and, if desired, C, wherein identical monomers A and B are selected in each case for the copolymers P1 and P2 and the 1st. formulation has a pigment volume concentration which is greater by at least 10 than that of the 2nd formulation, and to a composition of said 1st and 2nd formulations and to the use of said 1st and 2nd formulations for coating mineral moldings.

We claim: 
     
       1. A process for coating mineral moldings with film-forming aqueous formulations in which in succession at least one 1st formulation comprising at least one copolymer P1 as a binder and at least one inorganic pigment is applied to the mineral moldings, and then at least one 2nd formulation comprising at least one copolymer P2 as a binder pigment is applied, the copolymers P1 and P2 each being composed of monomers A, B and, optionally C, wherein: the monomers A are vinyl aromatic compounds (A1) and/or methacrylic esters of C 1  -C 4  -alkanols (A2),   the monomers B are esters, other than A2, of α,β-ethylenically unsaturated carboxylic acids with C 1  -C 12  -alkanols (B1) and/or vinyl esters of aliphatic carboxylic acids (B2), and the monomers C are different α,β-ethylenically unsaturated monomers,   wherein both copolymers P1 and P2 comprise either monomers A1 or monomers A2 or both P1 and P2 comprise monomers A1 and A2 as copolymerized monomers A and both P 1 and P2 comprise either monomers B1 or monomers B2 or both P1 and P2 comprise monomers B1 and B2 as copolymerized monomers B, with the proviso that: either identical monomers A and B are selected for the copolymers P1 and P2 or   the monomers A in P1 and P2 differ in their carbon number by not more than 2 carbon atoms and/or the monomers B in P1 and P2 differ in their carbon number by not more than 2 carbon atoms, and   the 1st formulation has a pigment volume concentration which is geater by at least 10% than that of the 2nd formulation.     
     
     
       2. The process as claimed in claim 1, wherein the applied 1 st  formulation is dried and the at least one 2 nd  formulation further comprises an inorganic pigment. 
     
     
       3. The process as claimed in claim 1, wherein the monomers B in P1 differ in their carbon number from the monomers B in P2 by not more than 2 carbon atoms and the monomers A for P1 and P2 are identical. 
     
     
       4. The process as claimed in claim 1, wherein the proportions of A to B in the copolymers P1 and P2 differ from one another by less than 30%. 
     
     
       5. The process as claimed in claim 1, wherein the copolymers P1 and P2 each contain at least 80% by weight of copolymerized monomers A and B. 
     
     
       6. The process as claimed in claim 1, wherein the copolymer P1 and P2 have glass transition temperatures T g  (P 1) and T g  (P2) in the range from -25 to +80° C. 
     
     
       7. The process as claimed in claim 1, wherein the 1st formulation has a pigment volume concentration in the range from 15 to 55 and the 2nd formulation has a pigment volume concentration in the range from 0 to 45 and the pigment volume concentration in the 1st formulation is greater by at least 10% than that of the 2nd formulation. 
     
     
       8. The process as claimed in claim 1, wherein the overall dry add-on of the 1 st and 2nd formulations is in the range from 50 to 400 g/m 2 . 
     
     
       9. A process for coating mineral moldings with film-forming, non-foaming aqueous formulations in which in succession at least one 1st formulation comprising at least one copolymer P1 as a binder and at least one inorganic pigment is applied to the mineral moldings, and then at least one 2nd formulation comprising at least one copolymer P2 as a binder pigment is applied, the copolymers P1 and P2 each being composed of monomers A, B and, optionally C, wherein: the monomers A are vinyl aromatic compounds (A1) and/or methacrylic esters of C 1  -C 4  -alkanols (A2),   the monomers B are esters, other than A2, of α,β-ethylenically unsaturated carboxylic acids with C 1  -C 12  -alkanols (B1) and/or vinyl esters of aliphatic carboxylic acids (B2), and   the monomers C are different α,β-ethylenically unsaturated monomers,   wherein both copolymers P1 and P2 comprise either monomers A1 or monomers A2 or both P1 and P2 comprise monomers A1 and A2 as copolymerized mononers A and both P1 and P2 comprise either monomers B1 or monomers B2 or both P1and P2 comprise monomers B1 and B2 as copolymerized monomers B, with the proviso that: either identical monomers A and B are selected for the copolymers P1 and P2 or   the monomers A in P1 and P2 differ in their carbon number by not more than 2 carbon atoms and/or the monomers B in P1 and P2 differ in their carbon number by not more than 2 carbon atoms, and the 1st formulation has a pigment volume concentration which is greater by at least 10% than that of the 2nd formulation, and   wherein the formulation contains at least one auxiliary selected from the group consisting of wetting agents, fungicides, defoamers, thickeners, antifreezes, flow promoters, plasticizers and film-forming agents.